Supramolecular Self‐Organization of “Janus‐like” Diblock Codendrimers: Synthesis, Thermal Behavior, and Phase Structure Modeling

Abstract

We report on the design and synthesis of three series of segmented amphiphilic block codendrimers, and on their self-organizing behavior in liquid-crystalline mesophases. Connecting two prefunctionalized monodendrons, each differing in their chemical constitution and generation number, yielded these diblock supermolecules. One wedge of the codendrimer was made hydrophobic, and is based on a branched poly(benzyl ether) monodendron functionalized at the periphery by lipophilic aliphatic fragments (also known as Percec dendrons). The other segment was made hydrophilic by the grafting of hydroxyl-containing moieties onto the focal functions of the former dendrons. Both types of dendrons were prepared independently by convergent methods and then joined in the ultimate stage of the synthetic procedure by cross-coupling reactions. In this way, the proportion of the dendritic blocks was varied independently to allow control of the hydrophilic/hydrophobic balance (HHB), the hydrogen-bonding ability, and consequently the capacity to tune the mesomorphic properties of the resulting "superamphiphiles" was anticipated. Essentially all the dendritic compounds display a thermotropic mesomorphism directly at or near room temperature as determined by using X-ray diffraction, polarized optical microscopy, and differential scanning calorimetry. The nature and the supramolecular organization of the mesophases, namely columnar and cubic phases, are correlated to the size of the respective block monodendrons and the chemical structures of the dendromesogens. The molecular organization within the cubic phases can be geometrically described and well understood by the space-filling polyhedron model.

Counterion Effects on the Columnar Mesophases of Triphenylene‐Substituted [18]Crown‐6 Ethers: Is Flatter Better?

“…Additionally, fragmentation of 2 e was observed under the conditions of the MALDI experiments. Up to three side chains were cleaved, giving rise to fragment ions [MÀC 11 + at m/z = 2023.1. Surprisingly, the complex KBr·2 e showed little tendency to undergo fragmentation and only one side chain was cleaved under MALDI conditions, yielding a potassiumcomplexed fragment ion [M+KÀC 11 H 23 ] + at m/z = 1908.9 and an uncomplexed fragment ion [MÀC 11 H 23 ] + at m/z = 1869.8.…”

“…The X-ray diffraction patterns of KSCN·2 c and KSCN·2 e are almost identical, but for KSCN·2 e more reflections are observed, which may be indexed as (11), (20), (02), (12), (22), (31), (13), (32), (23), (41), (14), and (43) ( Table 1, Figure 9c). Reflections with h+k = 2n+1 exclude c2 mm symmetry for the mesophases of KSCN·2 c and KSCN·2 e. The (20) reflection indicates a glide line normal to the crystallographic y-axis and the (02) reflection indicates the same symmetry element normal to the x-axis.…”

“…[8][9][10][11] Recently, we reported on dibenzo [18]crown-6 derivatives 1 with two lateral ortho-terphenyl units and their complexes MX·1 (M = K + , NH 4 + ). [12] It turned out that the anion X has a much stronger effect on their properties than the alkyl chain length.…”

Arrays of giant octagonal and square cylinders by liquid crystalline self-assembly of X-shaped polyphilic molecules

“…To each of its ends, a glycerol groups (A) was attached, capable of forming a cooperative and dynamic hydrogen-bonding network. Hence, these compounds represent Janus-type [27][28][29][30][31][32][33] X-shaped quaternary amphiphiles. An equivalent series of compounds 2 was also synthesized, having a shorter C 10 F 21 segment instead of the C 12 F 25 segment.…”

Spontaneous bulk organization of molecular assemblers based on aliphatic polyether and/or poly(benzyl ether) dendrons

“…These mostly contain mesogenic dendrons, for example, Percec-type poly(benzyl ether) dendrons, as their basic building unit. [43][44][45] On the other hand, despite several reports suggesting the synthesis of block codendrimers carrying nonmesogenic dendrons, 46-48 only a few self-assembling codendrimers have been reported, 49,50 and only a lamellar morphology has been found in the melt.…”